Error getting a simple example to work in Rails / Turbo / Hotwire-CodePudding

I am learning Hotwire-rails, following both the gorails.com and the Hotwire.dev examples. I am running Ruby 3.0.2 and Rails 6.1.4.1. The symptom is at the very start. After rails new xxx, I edit Gemfile to add gem 'hotwire-rails', then bundle install. At this point my app/javascript/packs/application.js is now:

cat app/javascript/packs/application.js 
// This file is automatically compiled by Webpack, along with any other files
// present in this directory. You're encouraged to place your actual application logic in
// a relevant structure within app/javascript and only use these pack files to reference
// that code so it'll be compiled.

import Rails from "@rails/ujs"
import Turbolinks from "turbolinks"
import * as ActiveStorage from "@rails/activestorage"
import "channels"

Rails.start()
Turbolinks.start()
ActiveStorage.start()

So that looks ok. But then rails Hotwire:install. Here is what I see (with the error messages in red.) It is as if it can't find the file.

/mydev/public_samples/rails/hotwire_error (master) rails hotwire:install
Create controllers directory
      create  app/javascript/controllers
      create  app/javascript/controllers/index.js
      create  app/javascript/controllers/application.js
      create  app/javascript/controllers/hello_controller.js
You must import "./controllers" in your JavaScript entrypoint
Install Stimulus
         run  yarn add @hotwired/stimulus from "."
yarn add v1.22.10
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